The present invention relates to a heat exchanger and more particularly to a heat exchanger of the counter-flow type for use in a Joule-Thomson type of refrigerator.
A conventional heat exchanger of the counter-flow type is disclosed, for example, in Japanese Patent Publication No. 44-6313. This patent discloses a heat exchanger having a cylindrical casing which houses a plurality of stacked wire nets. A bonding agent in the form of annularly-shaped elements interconnects adjacent wire nets. The bonding elements together form a cylindrical wall which defines two separate flow passages within the casing. High temperature gas is passed through one of the two flow passages. Low temperature gas is passed through the second flow passage in a direction opposite that of the high temperature gas. Heat is transferred from the high temperature gas to the low temperature gas through the plurality of wire nets. However, because the wire which forms the net is of such a high gauge (small radius), the efficiency of heat transfer from the high temperature gas to the low temperature gas is relatively low.
Accordingly, it is an object of the present invention to improve the efficiency of heat transfer in counter-flow heat exchangers of the type disclosed in Japanese Patent Publication No. 44-6313. This object and others are achieved by employing a thin walled metal pipe in place of the cylindrical wall formed by the bonding agents of the heat exchanger disclosed in the Japanese patent reference. The present invention increases the efficiency of heat transfer in the heat exchanger from the high temperature fluid to the low temperature fluid due to the increased surface area for heat transfer.
The present invention relates to a heat exchanger having a casing and at least one pipe disposed within the casing. Two flow passages are provided within the casing for directing the flow of fluid through the heat exchanger. A first flow passage is defined within the pipe. A second flow passage is defined between the pipe and the casing. A plurality of wire nets are disposed within each of the flow passages in order to facilitate heat transfer between fluids passing through the passages.